Smithsonian asked Scott Sillett, a wildlife biologist at the Smithsonian Migratory Bird Center.
Nature News: Bluebirds aren't blue, but use structural coloration
Bluebirds' vibrant colors and sweet warble thrill, but they're not the hardiest and might need help - Cambridge Day
Why Is Blue So Rare in the Animal Kingdom?
Wild Birds Unlimited - Nature Shop
ECHS - Blue in Nature - Early College and CCP - Research Guides at Rowan-Cabarrus Community College
Smithsonian Insider – Migratory Bird Center
Smithsonian Insider – John Gibbons
Eastern Bluebird
There is No Such Thing as a Blue Bird – National Geographic Education Blog
Smithsonian Sparks, Page 5
Nature News: Bluebirds aren't blue, but use structural coloration
20 Most Beautiful Types of Blue Birds (With Pictures)
Myosotis sylvatica 'Early Blue Bird' Forget Me Not
Pacific NW Birder: March 2011
Smithsonian Insider – John Gibbons
